1. Field of the Invention
The present invention relates to an Internet Protocol Version 6 (IPv6)-based mobile system. More particularly, the present invention relates to an apparatus and method for neighbor discovery in an IPv6-based mobile system using an Institute of Electrical and Electronics Engineers (IEEE) 802.16 link.
2. Description of the Related Art
IPv6 is a next generation Internet protocol that has been developed by the Internet Engineering Task Force (IETF) to solve problems of IPv4 currently used on the Internet. Neighbor discovery is a very important process in the operation of the IPv6. Nodes use the neighbor discovery to determine the link-layer addresses for neighbors known to reside on attached links. A node includes a host and a router.
Conversely, since broadband wireless access provides broadband communication without a wire, a larger amount of research with respect to the broadband wireless access has been conducted. According to the research, the Institute of Electrical and Electronics Engineers (IEEE) created IEEE 802.16 as a broadband wireless access specification, thereby causing a focus of research on broadband communication using EEE 802.16. IEEE 802.16 is a standard for a wireless air interface for wireless metropolitan area network (MAN)
FIG. 1 is a diagram illustrating a network in which mobile stations 101, 102, and 103 are connected to a base station 104 by an IEEE 802.16 link form an IPv6 link with access routers 105, 106, and 107. In FIG. 1, the mobile stations 101, 102, and 103 are connected to the base station 104 by the IEEE 802.16 link. The mobile stations 101, 102, and 103 are connected to the access routers 105, 106, and 107 by the IPv6 link. Namely, the mobile stations 101, 102, and 103 and the access routers 105, 106, and 107 for an IPv6 network in which the mobile stations 101, 102, and 103 and the base station 104 use the IEEE 802.16 link.
As described above, in IPv6, neighbor discovery must be performed. For transmission of a message to a destination from the mobile stations 101, 102, and 103, the base station 104 must know a link layer address of a next hop to which the message received from the mobile stations 101, 102, and 103 will be transmitted. This process of looking for the link layer address of the next hop to which the message will be transmitted is known as neighbor discovery.
However, there have been no standards with respect to neighbor discovery operation on the IEEE 802.16 network until recently. From a viewpoint of IPv6 neighbor discovery, the base station 104 is just a link-level bridge. However, unlike IEEE 802.11, in IEEE 802.16, the base station 104 uses a connection identifier (CID) instead of a Media Access Control (MAC) address, thereby always operating as a termination point with respect to communication. Even though a message is received from the mobile stations 101, 102, and 103, the base station 104 has no way of determining where the message should be transmitted.
FIG. 2 is a diagram illustrating an IEEE 802.16 MAC header used in the IEEE 802.16 link between the mobile stations 101, 102, and 103 and the base station 104. As shown in FIG. 2, a field capable of storing a link layer address of a next hop is not defined in the IEEE 802.16 MAC header. In the IEEE 802.16 link, the mobile station 103, for example, uses CIDs 201 and 202 for communication with the base station 104.
As described above, IEEE 802.16 does not provide any solution with respect to the neighbor discovery operation. Therefore, a method in which a mobile station transmits an IEEE 802.16 header including an Ethernet header to a base station has been provided. However, according to the method, a frame including fields for the Ethernet header, which are not used, must be transmitted.
Accordingly, there is a need for a neighbor discovery function that facilitates the operation of IPv6 with respect to a link technology that does not provide the neighbor discovery operation, such as IEEE 802.16.